Seat belt retractor

Abstract

A seat belt retractor has a spool mounted for rotation in the retractor for retraction or pay-out of seat belt webbing depending upon the direction of rotation of the spool. A locking ring is attached to one end of the spool. A device for locking locks the locking ring against rotation in a crash. A force limiting device allowing further pay-out of the seat belt webbing after the locking ring has locked, under the influence of a vehicle occupant's forward momentum. The force limiting device has a length of wire, attached at one end to one of the spool or the locking ring, and wound, at a distance spaced from said one end, on a pin fixed to the other end of the spool or the locking ring. Under the influence of crash forces above a predetermined value the wire is pulled around the pin.

What is claimed is:  
     
       1. A seat belt retractor comprising: 
       a spool, mounted for rotation in the retractor for refraction or pay-out of seat belt webbing depending upon the rotation direction of the spool;  
       a locking ring attached to one end of the spool, whereby a pin being fixed to the locking ring;  
       a means for locking the locking ring against rotation when a crash is sensed; and  
       a means for force limiting allowing further pay-out of the seat belt webbing after the locking ring has locked, under the influence of a vehicle occupant's forward momentum, wherein the means for force limiting comprises a length of wire, the wire is wound round the pin a multiple number of turns; and  
       a spindle being fixed to the spool, the wire is attached to one end of the spindle whereby under the influence of crash forces above a predetermined value, the wire is pulled completely around the spindle at least two turns.  
     
     
       2. The seat belt retractor according to  claim 1  wherein the spindle has a hole therethrough whereby the end of the wire is anchored therein. 
     
     
       3. The seat belt retractor according to  claim 1  wherein the wire is wound around only one pin, whereby under the influence of crash forces above a predetermined value, the wire is wound around the spindle in a spiral formation in the direction of the locking ring. 
     
     
       4. The seat belt retractor according to  claim 1  wherein the wire contacts the spindle and the pin, whereby under the influence of crash forces above a predetermined value, only the spindle and the pin influence the bending of the wire.